Help with possible causes for 7wk old chicken death
When my baby turkeys have coccidiosis I treat them with a couple teaspoons cayenne pepper per turkey for 2 or 3 days and that usually gets them better. Hope this helps if you need it.
The best way would be to mix it with their food but putting it in their water would be good too. I'll be offline for a while today, leaving now, good luck!
It's pretty contagious, but bloody poop can be caused by any number of things. My hens always have bloody poo for a few days after they start laying. I've seen bloody poop in a coop of perfectly healthy chickens, who remained healthy, and there never was any problems or other bloody poop.
It sounds like what happened when a couple of my chicks got ahold of a poisonous mushroom. Scour the area. If you see any mushrooms any colour other than white, especially if they're red, dispose of them.
I'm pretty sure it's nothing like that as they only have access to a temporary run area about 10x10 on my lawn and I never seen anything growing there other than grass :) They only thing they have had in the past two weeks other than their regular crumble is apples, cabbage, and a banana. I don't think those things would have caused any problem except for the fact the Hawk ate most of the banana over a day or two since the other chickens didn't really seem to care for it.
I would be concerned about possible coccidiosis in a 7 week old who is puffed up and lethargic. They can have blood in the droppings for 3 days before they start to show symptoms. Sulfadimethoxine and Sulmet are also used to treat the worst strains of coccidosis, although Corid can treat more strains. You can feed some buttermilk to help coat the GI tract until you get the Corid or sulfa drug. A necrospy done on your sick chick may show some hemorrhage inside the intestines. The first link below has pictures of that. Here are some articles about cocci: